Abstract
Abstract: The organic farming requires reducing the application of chemical fertilizer and herbicide, and the weeds play a critical role in confronting the world food security which requires high yield crops. In order to solve the problem mentioned above, the mechanical weeding control device is being highlighted nowadays. In terms of the mechanical weeding components, there are finger weeding device, torsion weeding device, brush weeding device with vertical axis, spring tine harrow, and so on. Separating the crop seedlings and the weeds is the key procedure during the weeding control process, and the spectrum, and spectrum pictures, as well as the machine vision are major technologies, but one thing should be mentioned that these sensors are relatively expensive and robotic weeding device equipped with these sensors seldom can be found in agricultural field yet. Thus based on the design concept of not relying on the intelligent guide platform or agricultural robot, this manuscript developed a mechanical weeding device equipped with a flexible shaft, a travel switch, a stepper motor, an MCU (microcontroller unit), 3 brush plates, and so on. This device was designed to serve the inter-tillage maize (Zea Mays L.) field, owing to that the maize plants in this growing period are high and vigorous enough to block the flexible shaft so as to turn on the travel switch. According to the division of maize breeding period, the maize plant at that time was in the stage of elongation, at which the male ear was elongated, the total length of the base stem node should be between 2 and 3 cm, and the leaf age index was about 30. In normal working status, one of the 3 brush plates is perpendicular to the moving direction, the bottom of the brush teeth will stab into the soil so as to pull the weeds out, and the device moves along with the tractor equipment. If there is a connection between the maize stalk and the flexible shaft, the flexible shaft will bend, and thus the travel switch will be turned on. Subsequently, the stepper motor will start working and the brush plate which would damage the maize stalk will rotate by 120? anticlockwise, so as to avoid the nearest maize stalk. If the forward speed of the device and the rotation speed of the brushes don't match, maize seedlings will be damaged, and thus a program was written in the MCU to achieve an appropriate relationship between the forward speed and the rotation speed. The software SPSS 22.0 was applied to conduct an orthogonal test, the soil bin laboratory in Jilin University provided the essential equipment, and the test indices were seedling damage rate and weed removal rate, and the test factors were seedling distances (17, 20, 23, and 26 cm), forward speeds (3, 4, 5, and 6 km/h), as well as the stabbing depths of the brush teeth (5, 10, 15 and 20 mm). There was no interaction between any 2 test factors, and 16 experiments were conducted. The maize plants and green bristlegrass (Setaria viridis (L.) Beauv.) were transplanted into the soil bin. The experimental results showed that under the most optimized test levels, the average seedling damage rate was 5.9%, and the average weed removal rate was 94.7%. The ANOVA (analysis of variance) results showed the seedling distance had significant (P<0.05) influence on seedling damage rate, and the brush stabbing depth had significant (P<0.05) influence on both seedling damage rate and weed removal rate, but the forward speed didn't have significant (P>0.05) influence on either seedling damage rate or weed removal rate. This device can meet the requirement of intra-row weeding control in maize field, and it is easy to manufacture and cost-effective, and thus it can become a reference for farming mechanical weeding device.
DownLoad: